"Bats use a lot of different types of sounds, from singing to each other to find a mate and to using echoes from their tweets to find their way around, " explained Kate Jones, joint University College of London (UCL) and Zoological Society of London (ZSL) chairwoman of ecology and biology.

"Usually, bat sounds are inaudible to humans as they are too high for us to hear but special 'time expansion' ultrasonic detectors convert these sounds to a lower frequency," Prof Jones, who is also chairwoman of the UK Bat Conservation Trust, explained.

"Visitors to the Bat Detective website can listen to these unique recordings and help us distinguish different sounds."

"We hope hundreds of thousands of people will help us listen in to what the bats are saying and to also build important tools for conservation," said Dr Chris Lintott from the University of Oxford, who led the team that designed and built the website.